Ronin might be cute, it means samurai with no master although you're it's master which is ironic but still cute :3
maybe something with 'kuro' since it means black, or Tama.
Then again there's Nyanko-sensei or Poyo if you want to name it after cat characters

Isn't your cat's surname supposed to be your surname, or the given name of its mother? In old Scandinavia children inherited their father's given name in their surname, so if their father's name was Peter, their surname would be Petersson (Peter's son) or Petersdottir (Peter's daughter).

I would pick Rei or Yui.
They don't mean anything to me, but they're simple enough.

I always pick simple names.
Next time I get a cat I will call it "Kos". Kose [kos-uh] means "Cuddle" in Norwegian.